This invention relates to a filtration/separation apparatus used primarily for dehydrating bean jam or squeezing a soy sauce or bean milk, though its application is not specifically limited to food-stuffs.
There has heretofore been known from, for example, Japanese Patent Application Laid-Open No. 150415/1982 filed by the present applicants, a filtration/separation apparatus including a rotor having a plurality of vanes radially provided thereon, and a filter cloth arranged to be fed around the rotor to form an eccentric arc with respect to a center of rotation of the rotor whereby a material to be processed is fed between the filter cloth and the rotor and is discharged from a part where a space between the filter cloth and the rotor is narrower than that at the feeding part.
However, in accordance with the conventional filtration/separation apparatus, it would be impossible to keep desirable contact positional relations between tip ends of the vanes and the filter cloth, and it would be difficult to obtain satisfactory filtration or dehydration effect. An example of this type will be explained in more detail with reference to FIG. 1, in which a cylindrical rotor 1 is adapted to rotate about a first center P.sub.1 and is provided with a plurality of radially retractable vanes 2. An arcuate support means 3 has a second center P.sub.2 which is eccentric with respect to the first center P.sub.1. A filter cloth 4 is arranged between the rotor 1 and the support means 3. The filter cloth 4 is adapted to pass along an outer surface of the support means 3 on the arc having the center P.sub.2. Rollers 5 and 6 are used for folding back the filter cloth. A hopper 7 is provided for feeding a material to be processed between the rotor 1 and the filter cloth 4. A stripper or blade 8 is provided for scraping the material stuck on the filter cloth 4. Incidentally, it is apparent that a pair of side plates (not shown) are provided to close portions which extend at least from a supply port 9 of the hopper 7 to a take-out port 10 for the material to be processed as viewed in the rotational direction F.sub.1 of the rotor 1 and are defined by opposed end portions of the rotor 1 and opposed end portions of the filter cloth 4. With such a construction, when the rotor 1 is rotated in the direction F.sub.1 while the filter cloth 4 is fed in the direction F.sub.2 and the material to be processed is fed from the hopper 7, the space chamber A defined by the space between the cylindrical surface of the rotor 1 and the filter cloth 4 and the pair of side plates is gradually narrowed in accordance with the rotation of the rotor 1. Therefore, a pressure in the space chamber A is increased, and if the filter cloth 4 is used for the purpose of dehydrating, water components contained in the material to be processed are filtrated or removed through the filter cloth 4 to the outside of the space chamber A. As a result, the material which has been dehydrated is discharged from the take-out port 10.
However, in the filtration/separation apparatus with such a construction, since a distance between the tip ends of the adjacent vanes 2 (for example, distances L.sub.1 or L.sub.2) is gradually decreased according to the advance of process, the position where the tip end of the vane contacts with the filter cloth 4 would be changed, and the filter cloth would be loosened, so that an excess filter cloth portion would be folded since a relatively high pressure is applied to the interior of the space chamber A. In other words, there is a fear that when the position where the tip end of the vane 2 contacts with the filter cloth 4 is displaced, the filter cloth 4 and the tip end of the vane 2 would be damaged or abraded. In addition, since the material to be processed tends to be leaked from the higher pressure space A to the lower pressure space A due to the displacement of the contact position, it would be difficult to maintain a high dehydration efficiency (or filtration efficiency). Moreover, if the loosening or folding is generated in the filter cloth 4, this part would be damaged or abraded, so that it would be difficult to provide a long service life of the filter cloth 4.